Taming Molecular Boron Nitride through a Tandem Donor-Acceptor Stabilization/Arene Release Strategy

Boron nitride (BN) is a highly reactive 8 valence electron diatomic molecule, unstable under ambient conditions; however, at temperatures >900 °C, ceramic (BN)n polymorphs can be prepared. Isoelectronic to carbon isosteres such as diamond, graphite, and carbon nanotubes (CNTs), (BN)n polymorphs exhibit remarkably different properties owing to the highly polar B-N bonds. The high temperature synthesis of (BN)n materials preclude the isolation and study of molecular BN. Herein, we report the synthesis of EtCAAC-B≡N-B(C6F5)3, a donor-acceptor stabilized molecular boron nitride. Single-crystal X-ray diffraction as well as nuclear magnetic resonance, infrared, and Raman spectroscopic studies coupled with density functional theory calculations support the notion that the central B≡N unit exhibits triple bond character. Preliminary reactivity indicates that this compound does not react analogously to structurally similar iminoboranes as evidenced by the thermal extrusion of the central boron and nitrogen atoms.